The present technology relates to a simulation method and a simulation program for predicting a processing state of a processing target, and to a processing apparatus, a simulator, and a design method that utilize the simulation method.
In a plasma etching simulation of a semiconductor, an incident radical amount and an incident ion amount entering a pattern are calculated, and an etching rate is derived by solving a reaction at a processing surface with use of the calculation result. Shape development is calculated from the etching rate. In the calculation of the incident radical amount, two calculations are made to determine a “direct component” which enters a processing surface element from immediately above the pattern and an “indirect component” which is once reemitted from other processing surfaces and enters the processing surface element. The calculation of the indirect component is particularly important factor for predicting a processing shape.
As a method of calculating the indirect component, a method that uses Monte Carlo method and a method that uses a flux method have been known. Although the former can accurately reflect the physics, more test particles are needed as an aspect ratio of a target pattern become higher, so that a calculation time becomes enormous. Meanwhile, although the latter does not accurately reflect the physics, when modeling is performed well, the latter reduces a calculation cost and can be a useful calculation technique.
As a typical method of calculating the flux method, for example, a method described in Tuda et al., J. Appl. Phys. 81 (1997) 960 (hereinafter, referred to as Non-Patent Document 1) has been known. This method assumes that the indirect component is reemitted only once from other elements and is calculated by using an angle (φ) made by a vector connecting normal vectors of two surface elements and element centroids, a distance (r) between the centroids, a residual flux ((1−S)Γ), and a surface element area (dS) as an argument.
Meanwhile, a calculation technique that uses the flux method has been also proposed in Japanese patent No. 2803649 (hereinafter, referred to as Patent Document 1). This technique is a calculation technique limiting a pattern to an axisymmetric hole shape, and integrates and derives a reemission from a minute element on a circumference cut along a surface (X-Y plane) perpendicular to a cylindrical axis with respect to an angle (θ) made by an X-axis and the minute element on the circumference.